cf topology lessons... pls help

[Pjotr]

A good CF is a blessing for any tube design, trying to do without is akin to looking for problems where there aren't any IMHO.

Can second that for a well set up CF but no CF is the Holy Grail.

Tubes are very good voltage amplifiers but poor current amplifiers if it comes to low distortion. You get the lowest distortion if the current through the tube does not change at all. The trick is to have a lot higher standing DC current through the tube than the peak current asked by the load (which includes the cathode resistor for a CF). So you need to bias the grid above ground (say 50V) to allow for a high enough cathode resistor or use a negative voltage to tie the cathode resistor to, or use a CCS at the cathode. I am not a fan of the WCF and the Broskie contraptions are, uh well, unnecessary complex IMHO.

Cheers

[SY]

A good CF can be (and vide Pjotr, OUGHT to be) quite simple, but MUST run a decent a mount of current. With those in mind, the source/sink thing is pretty much moot as you can prove to yourself by attaching a cable plus load to the output of the CF, banging the input with some square waves, and noting that the rise and fall times are far better than you actually need- or can be actually provided by the signal sources.